#ITEM PAID NO FUNDS

I have a FNB premier debit account and for the past 3 months I have been paying more than R600 per month in addition to my bank charges. The bank says it is because there is not enough funds in the account and this is for unpaid transactions but this does not make sense as I have a debit card and every time I spend money my balance decreases which means I cant spend more than I have.

What individual pays R650.00 per month to the bank for service fees on a debit account. I am really not happy with this and am struggling to get it resolved.